The circular dichroism (CD) studies of bis-1,8-naphthalimide. The theoretical analysis in terms of density functional and vibronic dimer theories

► The vibronic analysis of the low-energy transitions in 1,8-naphthalimide done for the first time in literature. ► The first conformational study of bis-1,8-naphthalimide molecule treated as a symmetrical dimer consisting of two 1,8-naphthalimide monomers. ► The first comprehensive study of CD and absorption spectra of bis-1,8-naphthalimide molecule performed in terms of vibronic coupling dimer theory applied with parameters acquired from density functional theory (DFT) computations.